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UKMT Intermediate Mathematical Challenge, 2023

Algebra Difficulty 3.0 AMC 10/12 Find the answer United Kingdom

The numbers xx and yy satisfy both of the equations 23x+977y=202323x + 977y = 2023 and 977x+23y=2977977x + 23y = 2977. What is the value of x2−y2x^2 - y^2?

(A) 11 (B) 22 (C) 33 (D) 44 (E) 55

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